Compression of organs is another quite uncommon reason couple might experience problems when trying to conceive. In healthy person internal organs are positioned with little room for manoeuvre, which in case of inflammation can results in a major difference. For example, a constipation, which is a very common occurrence can cause colon to be filled with waste and therefore swell. Since the part of the colon in women works around the uterus and fallopian tubes, consequently this can interfere with the healthy blood supply. In males, colon swelling can interfere with prostate gland.
Another very common cause of infertility which is rarely shown on tests is stress. A couple can be otherwise very healthy, but the stress might be the reason for their problems. Sometimes stress is shown only mentally, but sometimes the impact can be physical too: it is shown in a form of skin disease, problems with sleeping or infertility. There is an evidence, that suggests that stress causes the adrenal gland to excrete stress hormones and this can block both not only fertility, but the sex drive too.
Another relatively rare reason can be toxicity. Toxicity can be caused by additives in foods, from medications, either prescription medications or over the counter drugs. Metals that are found in fish can be a cause, and a relatively common reason can be contaminated water. Sometimes pesticides found in fruit and vegetables, and artificial hormones and antibiotics in found meat and dairy products can contribute to infertility.